I. Technical Field
This invention relates generally to an apparatus for measuring the area of a three dimensional configuration such as a non-planar vehicle door panel and, more particularly, to a measuring tool which is attachable to a computerized or digitalized manually operated measuring machine.
II. Discussion
In the design, development and manufacturing of a three dimensional component such as a vehicle door or body side panel it is important to measure the actual area of the entire surface, including edges and arcuate portions, to ascertain whether the component meets required specifications. Another important function, among others, is to determine specific points along the component at which work operations are to be performed. Such work operations may include drilling holes for the attachment of fasteners and a determination of points for the application of adhesives used in the manufacturing process, as well as numerous other procedures.
One mechanism which is useful in performing such measurements is a coordinate measuring machine such as the model G80C manufactured by LK, which is a Cincinnati Milicron Company. Typically, these coordinate measuring machines are movable along three axis, namely the x, y and z axis, and serve to supply a computer with information as to datum points located on the workpiece. From these datum points, a computer which is integrally connected to the coordinate measuring machine can automatically calculate surface areas and other features of the workpiece being measured.
One problem with manually operated coordinate measuring machines is that various probes are necessary to contact different points on the surface of a contoured component. For example, a linear probe is generally used to obtain datum information along planar portions of the workpiece. Then, for the contoured surfaces a second probe which has a specific shape such as an overall L-shape or a hook must be attached to the coordinate measuring machine to make contact with the contoured portions. Often a set of probes numbering five or more is needed to obtain the desired datum information from a contoured workpiece.
The use of multiple probes is time consuming in that substantial time is required to attach and detach the various probes to the coordinate measuring machine. Further, the use of multiple probes leads to inaccuracies in the readings which are taken. When a probe is attached, the coordinate measuring machine is calibrated to insure the accuracy of the readings. Each time a different probe is attached a new calibration must be conducted to help insure that consistent datum point information can be collected. This necessity of recalibrating each time an alternative measuring tool is attached also leads to the possibility of inaccurate readings and is obviously unnecessarily time consuming.
The present invention eliminates the above described problems as well as many others by providing a single measuring tool for use with a manually operated coordinate measuring machine or other such machine which is capable of contacting both planar and contoured portions of a workpiece to assist in providing datum point information in a highly accurate manner. This invention enables the operator to easily obtain datum point information over a contoured workpiece without having to reattach and substitute a variety of different probes for readings along differently shaped portions of the workpiece.